1. Field of the Invention
The present invention relates to cutting tools having a cutting unit including a circular blade and a movable cover that can move to open and close a part of the circular blade.
2. Description of the Related Art
A known desktop-type circular saw has a table for placement of a workpiece and a tool unit. The tool unit has a rotary circular saw blade and is vertically movable relative to the table, so that the workpiece is out by the saw blade by downwardly moving the tool unit.
The technique relating to this kind of cutting tool is disclosed, for example, in Japanese Laid-Open Patent Publication No. 2009-226526. A tool unit of a desktop-type circular saw disclosed in this publication includes a unit case and an electric motor. The unit case rotatably supports a saw blade. The electric motor serves as a drive source. A movable cover covers the cutting edge of the saw blade within a range of an upper half of the circumferential length of the saw blade. The movable cover is opened in conjunction with the downward movement of the tool unit and is closed in conjunction with the upward movement of the tool unit. As the movable cover is opened in conjunction with the downward movement of the tool unit, a workpiece is cut by the exposed part of the saw blade.
However, in general, this kind of movable cover has a unique shape having a fishhook-like vertical cross sectional configuration that is not symmetrical in the right and left direction. The movable cover has a fan-like side view as viewed in an axial direction of the rotational axis of the saw blade. Therefore, in the case that the movable cover is molded by resin, the size and shape of the movable cover may not be always stable. For example, in some case, the movable cover may be positioned to be excessively close to the fixed cover when it is assembled. As a result, it is necessary to improve the molding accuracy or to strictly control the size. This may lead to increase the manufacturing cost.
Therefore, there is a need in the art for enabling the movable cover to be suitably positioned relative to the saw blade and the fixed cover.